In the related art, camera systems are utilized for scanning moving surfaces, such as a freshly fabricated sheet of steal or aluminum, in order to monitor an analysis the moving surface for quality control purposes. For instance, a moving surface such as a freshly fabricated sheet of aluminum may be passed in front of camera system for the purpose of scanning the sheet of aluminum for defects. The defects could include external contaminants embedded in the aluminum sheet. In this example, the newly fabricated aluminum sheet passes infront of the camera system at a rate exceeding 1,000 feet per minute; oil and mist from the fabrication process is exists on the sheet and in the environment surrounding the camera. Furthermore, the environment typically exceeds a temperature of 150.degree. F.
The camera system is required to scan this moving surface under these adverse conditions. However, in this harsh environment, oil, dust, and other contaminants tend to accumulate on a lens of a scanning camera thereby destroying the optics of that lens. Moreover, mist or smoke between the scanning lens and moving surface tend to obscure the field of view of the scanning lens of the camera. This obscured field of view results in an inferior quality scan.
One approach to overcoming the accumulation of oil, dirt and other contaminate on the scanning lens of the camera is to place a piece of glass or other protective covering in front of the scanning lens. In this case, the camera is generally placed inside of a protective box and the lens views through an aperture covered by the glass or protective covering. However, even though the glass covering in front of the lens does in deed keep the lens itself becoming dirty, the glass covering becomes dirty and obscures the optics of the lens. Furthermore, a glass covering in front of the lens does not keep the mist and smoke between the lens and the moving surface from obscuring the lens. As a result, the glass covering requires high maintenance in terms of continuously cleaning the oil and contaminants from the glass surface without eliminating the smoke and mist occlusions.
Another approach to maintaining the optical integrity of the scanning lens of the camera is to put air curtains on the lens. The air curtains provide a screen of moving air between the scanning lens and the moving surface. However, the air curtains tend to mix compressed air with air from the environment surrounding the camera. Because the air from the environment surrounding of the camera tends to be oily, dirty and contaminated, these contaminants nonetheless tend to accumulate on the scanning lens over time. Furthermore, the air curtains did not protect the camera system from the harsh temperatures experienced in the environment.